Study On Key Technology For Encryption And Security System In Wireless Communication Network Hsien-Wei Tseng 1 Rong-Hou Wu 2 Chih-Yuan Lo 3 Yang-Han Lee 3 Liang-Yu Yen 3 1 Dept. of Computer & Communication, Engineering DE LIN Institute of Technology Tucheng,Taipei County, Taiwan 251, R.O.C hsienwei.tseng@gmail.com 2 Dept. of Computer & Communication, Engineering St. John's University Tamsui,Taipei County, Taiwan 251, R.O.C rhwu@mail.sju.edu.tw 3 Dept. of Electrical Engineering, Tamkang University Tamsui,Taipei County, Taiwan 251, R.O.C. grimmg@ee.tku.edu.tw yhlee@ee.tku.edu.tw skyslj@hotmail.com Abstract—A novel secure encryption using the recieved signal strength indicator (RSSI) has been proposed in this paper. RSSI signals are time variant and irregular, especially in more complicated environment. Changes of RSSI can generate a nonperiodical random number, and an attacker will hardly predict this number. Furthermore, we use this option, open cryptography algorithm, and rapid stream ciphers to construct an efficient encryption system for wireless communication network. Keywords-Encryption, Security system, I. INTRODUCTION Due to diversity transmission services, the new age communication system is facing more security issues than previous years [1-6]. The operation capability of computing equipement at the client end will for sure be much stronger in the next generation. Digital signature or Non-repudiation of information is the premise of commercial trade on the network; therefore, the demand for security system becomes more and more important. This is not what tradition Secret-key Cryptosystem can do. Presently, ITU-R (International Telecommunications Union – Radio communications Sector) is planning a security serverses which at least includes Authentication, Privacy and Anonymity, Confidentiality, Integrity, Authorization and Access Control, Event Limitation, and Event Reporting. A study of Security Mechanisms, ITU-R also presents three possible types: Secret Key Check Functionfor bi-direction I.D. authentication module, Digital Signature single direction I.D. authentication module, and Public-key Cryptosystem single direction I.D. authentication module. In accordance with high-speed wireless LAN IEEE 802.11 standard formulates the Wired Equivalent Privacy Algorithm (WEP), which has a equal function of data privacy algorithm as wire network. Stream Cipher technique [7-8] is the simplest and the fastest enciphering/deciphering method. Because of its limitation by hardware, it has a fixed period length, so it needs 2L output serier for feedback equations, where L is linear complicity. To overcome this imperfection, we fetch RSSI signals from IF (intermediate frequency) circuit of wireless communication, for generate random number. RSSI signals exchanged by environment are irregular, non-periodical, and have time variant. Therefore it is very suitable to use on password systems. The proposed encryption system in this paper uses the complicated environment RSSI characteristics, its unpredictable number, and the fact that wireless LAN’s application is always in complicated indoors transmission environment. So this encryption system is very suitable for wireless communication network. II. GENERATION OF ENVIRONMENT RANDOM NUMBER The multi-path effect and environment variable are the factors that change RSSI signals. A random number generate from this RSSI is called environment random number (ERN) in this paper. The flow chart of generating ERM is shown in Fig.1 and is described in details below. RSSI signal, which is fetched from IF circuit of wireless communication, is sampled and quantized after passing through a linear amplifier R(nT) = R(t)|t=nT , 0 n Where R(t) is RSSI signals, T is sample period, and R(nT) is discrete RSSI signal. Annual International Conference on Infocomm Technologies in Competitive Strategies (ICT 2010). Copyright © GSTF 2010. ISBN: 978-981-08-7240-3. doi:10.5176/978-981-08-7240-3 I-27 60